Pulse-generating apparatus

ABSTRACT

A condenser discharge-type electrical pulse-generating circuit, such as for a combustion engine ignition system, wherein two storage capacitors are charged in parallel and partially discharged in series through two control gaps and the primary winding of a high-frequency transformer, the secondary winding of which is connected in series with a high-voltage igniter gap and one of the condensers through one of said control gaps.

United States Patent 3,191,093 6/1965 Morrison et al. 315/209 3,450,9426/1969 Segall et al 317/227 X 3,450,972 6/1969 Linkroum 315/227 XPrimary Examiner-Roy Lake Assistant Examiner-Lawrence J DahlAttorneys-Raymond J. Hitler and Plante, Hartz, Smith and ThompsonABSTRACT: A condenser discharge-type electrical pulsegenerating circuit,such as for a combustion engine ignition system, wherein two storagecapacitors are charged in parallel and partially discharged in seriesthrough two control gaps and the primary winding of a high-frequencytransformer, the secondary winding of which is connected in series witha highvoltage igniter gap and one of the condensers through one of saidcontrol gaps.

A a; I I2 w 7 I9 \U H 22 PATENTED U502! [97! INVENTOR.

IRVING E, LlNKROUM ATTOR EYS PULSE-GENERATING APPARATUS This inventionrelates to electrical apparatus and more particularly to means forcontrolling the operation of electrical pulse or spark-generatingapparatus having an intermittently discharged storage condenser.

An object of the present invention is to provide novel control means foran electrical pulse or spark generating apparatus of the type indicated.

Another object is to provide a novel control means for an electricalpulse or spark-generating apparatus incorporating a storage condenserwhich is intermittently discharged through a control gap.

A further objectis toprovide meansfor controlling breakdown of thecontrol gap, such meansbeing subjected to only a small part of theenergy which is discharged through the control gap.

A still further object of the invention is to provide acontrol means forelectrical pulse-generating apparatus which is simple, rugged,'and longlived, and which .provides maximum power output for a given inputvoltage.

The above and further objects and novels features of the invention willmore fully appear from the following description when the same is readin connection withthe accompanying drawing. It is to be expresslyunderstood, however, that the drawing is for the purpose of illustrationonly, and is not intended as a definition of the limits of theinvention.

The single FIGURE of the drawing is a wiring diagram of one embodimentof an electrical pulse or spark generating circuit in accordance withthe invention.

The circuit shown in the drawing is adapted for use asan untimedignition circuit for jet and gas turbine type engines. The invention isnot, however, limited to such uses or systems.

The ignition circuit shown is of the condenser dischargetype which isenergized by a suitable source 13 of alternating electrical current or asource of interrupted direct current connected to input terminals A and-B of the ignition circuit. The current source is connected to theprimary winding .10 of a power input transformer 11 having a secondarywinding 12. The circuit includes a radiofrequency-filtering means 14which is preferably, although not necessarily .employed, the means 14being interposed between the power source and the transformer 11 toattenuate high-frequency noise generated within the ignition circuit andthus preventing interference from being transmitted to other circuitsconnected to the current source. I

A voltage-doubling type of energy storage means is con- Such storagemeans is incrementally charged by the energy source through transformer11; the energy storage means is periodically discharged to apulse-absorbing load, which in this instance is an ignition spark gap29. The storage means comprises a small condenser 15 which is connectedacross the secondary winding 12 through a diode or half-wave rectifier16, a second small condenser 17 connected across winding 12 through areversely polarized diode or half-wave rectifier 19, and a mainrelatively large tank condenser connected across condensers 15 and 17 inseries. It will be apparent that with the diodes 16 and 19 connected asshown, when the condensers are being charged the lower terminals ofcondensers 15, 17 and 20 are negative whereas the lower terminal of acondenser 31, to be described, is positive. Thediodes 16 and 19 may beprotected against damage, the operating life thereof may be enhanced,and the required rating thereof may be minimized by providingcurrent-limiting resistors 21 and 22 in the circuit, as shown. One sideof the above-described'energy storage means is shown as being connectedto a common ground 23, and the high potential side thereof is connectedthrough a control or trigger gap to the ungrounded electrode of anignition spark gap 29. It will be understood that, if desired, all ofthe points in the circuit designated 23'may be connected by a commonungrounded conductor.

The input electrode 24 of the trigger gap 25 is connected to the highpotential side of the ignition circuit beyond the main tank condenser20.The output electrode 26 of the trigger gap 25 is connected to oneterminal of the secondary winding 27 of a step-up transformer 28, theother terminal of the secondary winding 27 being connected to theungrounded electrode of the ignition spark gap 29.

Connected across the electrodes 24, 26 of the trigger gap 25 is acircuit having a large resistance 30 and a small condenser 31 in series.Connected to the high potential side of the ignition circuit between thepoint of connection of the condenser 31 and the input terminal of thesecondary winding 27 of transformer 28 is one terminal of a smallresistance 33, the other terminal of which is connected to ground. Oneterminal of the primary winding 35 of the step-up transformer 28 isconnected between the resistance 30 and the condenser 31 through acontrol gap 36 having an input electrode 34 and a discharge electrode37, the other tenninal of the primary winding 35 being connected toground. The ionizing or breakdown voltage of the trigger gap 25 issubstantially less than that of the control gap 36 and much less thanthat of igniter gap 29.

In one successful embodiment the power transfonner 11 steps up thesupply voltage, which in this instance is assumed to be 400 cycle, ll5volt, to a level in excess of 1,600 volts peak. Each half-cycle of thisvoltage is rectified by one of the diodes 16, 19 to charge one of thedoubler condensers 15, 17. The voltage across condensers 15, 17 isadditive and therefore the voltage charging the main storage condenser20 and trigger condenser 31 is in excess of 3,000 volts peak and of gap25 breakdown voltage.

While the storage condenser 20 is being charged, condenser 31, which isthen connected in parallel therewith, is charged through resistance 30,the charging circuit for condenser 31 being completed to ground throughresistance 33. As above explained, with the diodes 16, 19 disposed asshown, the input electrode 24 of the trigger tap 25 is positive withrespect to the output electrode 26 thereof. When the voltage of thecharge on condensers 20 and 31 exceeds the ionizing voltage of triggergap 25, the trigger gap breaks down, the positive end of condenser 20,that is, that connected to electrode 24 of the trigger gap 25 ismomentarily connected through gap 25 to the negative terminal ofcondenser 31, whereby the condensers 20, 3,1 are momentarily connectedin series across gap 36 and their voltages are additive. Such addedvoltages, which are impressed on electrode 34 of control gap 36, exceedthe ionizing potential of the control gap 36. Gap 36 now begins todischarge the charge of the storage condenser 20, 31 through the primarywinding 35 of the step-up transformer 28 to ionize the igniter gap 29.While this is taking place, the trigger gap 25 remains conductive, andthe main part of the charge on condenser 20 is discharged to theignition gap 29 through the secondary 27 of transformer 28.

The discharge of condensers 20 and 31 through the control gap 36,through the primary winding 35 of the transformer 28, and thence toground results in a stepped-up voltage across the secondary 27 oftransformer 28. This high voltage, on the order of 15-20 kilovolts, isalso impressed across the output cable and the igniter plug 29. Once theinitial arc has formed across the igniter plug 29, the energy containedin the storage condenser 20 is channeled through the control gap 25, thesecondary winding 27 of transformer 28 and through the prefonned arc ofthe igniter gap 29 to ground.

This energy is tenned the follow-through". After the voltage across thetwo condensers 20, 31 decreases to low values,

their associated gaps 25, 36 deionize and the cycle repeats itself.

The circuit of the invention allows fewer turns to be employed in thesecondary 27 of the high-frequency transformer 28. Hence a higher peakdischarge current can be obtained through the secondary 27. Theseresults follow from the relationships:

Surge impedance and The reduction of the number of turns in thesecondary winding 27 reduces the value of L, and thus increases l andhence the peak power output for a given E. It should be noted that withthis type of circuit the trigger gap 25 controls the ionization of thecontrol gap 36. The normal ionization voltage of the gap 36 is muchhigher than the level at which gap 25 and hence at which the system istriggered.

Typical values of component parts which make up a satisfactory system asabove described are as follows:

Condensers 20 3.5-3.6 mi. 31 0.050.065 pf.

Resistances Ohms 2i and 22 2,000

Control Gaps Ionizing Potential 25 3,000 volts 36 3,500- 4,000 voltsAlthough only a single embodiment of the invention has been illustratedand described in the foregoing specification, it is to be expresslyunderstood that the invention is not limited thereto but may be embodiedin specifically different circuits. For example, the main tank orstorage condenser 20 may be incrementally charged through other knownvoltage-doubling systems or through a half-wave rectifier. Transformer11 may also be powered by an interrupted direct current source or solidstate oscillator. Various other changes may also be made, such as in theelectrical values suggested herein by way of example, and in the typesof rectifiers illustrated without departing from the spirit and scope ofthe invention, as will now be apparent to those skilled in the art.

What is claimed is:

1. Electrical apparatus having a source of electrical energy, amultisection storage condenser means connected to said source so as tobe incrementally charged thereby with the sections of the condensermeans connected in parallel, a load circuit connected to be energized bythe discharge of the storage condenser means, a first control gapinterposed between one section of the storage condenser means and theload circuit, a second control gap having a breakdown potential greaterthan that of the first control gap and less than the sum of the voltagesof the charges attainable by the parallel connected sections of thestorage condenser means, first circuit means connecting the first gap tothe storage condenser means so that the first gap is ionized andrendered conductive when the charge on the parallel connected sectionsof the storage condenser means reaches a predetermined voltage, andsecond circuit means for thereupon connecting said sections of thestorage condenser means in series, voltage-adding relation andsubjecting said gaps to the full voltage of the series connected storagecondenser sections so as to ionize the second control gap and render itconductive to the discharge of the storage condenser means.

2. Electrical apparatus according to claim 1, wherein the storagecondenser means has two sections, and said second circuit means includesthe second gap interposed between the junction between said sections anda common conductor to which the load circuit is connected.

3. Electrical apparatus according to claim 1, wherein another section ofthe storage condenser means is connected in shunt with the first controlgap.

4. Electrical apparatus according to claim 3, wherein said last-namedsection of the storage condenser means has a capacity which is but asmall fraction of that of said one condenser section.

5. Electrical apparatus according to claim 1, wherein the load circuitincludes an ignition spark gap.

6. Electrical apparatus according to claim 1, wherein the load circuitincludes a transformer winding, the first gap has entering and dischargeelectrodes, and the discharge electrode is connected to the said windingof the transformer.

7. Electrical apparatus according to claim 1, comprising a transformerhaving primary and secondary windings, and wherein the dischargeelectrode of the first gap is connected to one terminal of the secondarywinding.

8. Electrical apparatus according to claim 7, comprising an ignitionspark gap having one electrode connected to the other terminal of thesecondary winding, and wherein the second gap has an electrode connectedto the primary windmg.

9. Electrical pulse-generating apparatus comprising a source ofelectrical energy, first and second condenser means connected inparallel across said source to be simultaneously charged thereby, acondenser discharge circuit connected across said second condenser meansand comprising normally open circuit-closing means responsive to apredetennined charge on said second condenser means for closing saidcircuit, and a second condenser discharge circuit comprising othernormally open circuit-closing means and said first and second condensermeans connected in series across said firstnamed circuit-closing means,said other circuit-closing means being responsive to the sum of thecharges on said first and second condenser means to close said seconddischarge circuit while said first-named circuit-closing means isoperative.

10. Electrical pulse-generating apparatus comprising a source ofelectrical energy, first and second condensers connected to be chargedin parallel by said source, a first spark gap connected between thepositive polarity terminal of one of said condensers and the negativepolarity terminal of the other of said condensers, a second spark gapconnected between the other terminals of said condensers, and condenserdischarge circuit means including said second spark gap connected acrossand adapted to be rendered conductive by the charge on said secondcondenser, whereby said condensers and said second spark gap becomeconnected in series across said first spark gap while the second sparkgap is conductive.

11. Electrical pulse-generating apparatus comprising a source ofelectrical energy, first and second storage condensers connected inparallel across said source to be simultaneously charged thereby, afirst discharge circuit comprising said first condenser and a firstspark gap adapted to be rendered conductive by a predetermined charge onsaid first condenser, and a second discharge circuit comprising saidfirst gap and said first and second condensers connected in seriesacross a second spark gap having a spark-over voltage less than the sumof the charges on said condensers when said first gap is renderedconductive.

12. Electrical pulse-generating apparatus comprising a source ofelectrical energy, first and second storage condensers connected inparallel across said source to be simultane-- ously charged thereby,first and second normally conductive spark gaps, a first dischargecircuit comprising said condensers and said spark gaps connected inseries, and a second discharge circuit comprising said second condenserin series with said second spark gap, the latter being adapted to berendered conductive when said second condenser attains a predeterminedcharge, and said first spark gap being adapted to be rendered conductivein response to the sum of the charges on said condensers when saidsecond spark gap is rendered conductive. 1

13. Apparatus as defined in claim 12 comprising a transformer havingprimary and secondary windings, said primary winding being seriesconnected in said first discharge circuit, a third spark gap connectedacross said secondary winding, and a third discharge circuit comprisingsaid second spark gap, said secondary winding and said third spark gapconnected in series across said first condenser.

1. Electrical apparatus having a source of electrical energy, amultisection storage condenser means connected to said source so as tobe incrementally charged thereby with the sections of the condensermeans connected in parallel, a load circuit connected to be energized bythe discharge of the storage condenser means, a first control gapinterposed between one section of the storage condenser means and theload circuit, a second control gap having a breakdown potential greaterthan that of the first control gap and less than the sum of the voltagesof the charges attainable by the parallel connected sections of thestorage condenser means, first circuit means connecting the first gap tothe storage condenser means so thaT the first gap is ionized andrendered conductive when the charge on the parallel connected sectionsof the storage condenser means reaches a predetermined voltage, andsecond circuit means for thereupon connecting said sections of thestorage condenser means in series, voltage-adding relation andsubjecting said gaps to the full voltage of the series connected storagecondenser sections so as to ionize the second control gap and render itconductive to the discharge of the storage condenser means. 2.Electrical apparatus according to claim 1, wherein the storage condensermeans has two sections, and said second circuit means includes thesecond gap interposed between the junction between said sections and acommon conductor to which the load circuit is connected.
 3. Electricalapparatus according to claim 1, wherein another section of the storagecondenser means is connected in shunt with the first control gap. 4.Electrical apparatus according to claim 3, wherein said last-namedsection of the storage condenser means has a capacity which is but asmall fraction of that of said one condenser section.
 5. Electricalapparatus according to claim 1, wherein the load circuit includes anignition spark gap.
 6. Electrical apparatus according to claim 1,wherein the load circuit includes a transformer winding, the first gaphas entering and discharge electrodes, and the discharge electrode isconnected to the said winding of the transformer.
 7. Electricalapparatus according to claim 1, comprising a transformer having primaryand secondary windings, and wherein the discharge electrode of the firstgap is connected to one terminal of the secondary winding.
 8. Electricalapparatus according to claim 7, comprising an ignition spark gap havingone electrode connected to the other terminal of the secondary winding,and wherein the second gap has an electrode connected to the primarywinding.
 9. Electrical pulse-generating apparatus comprising a source ofelectrical energy, first and second condenser means connected inparallel across said source to be simultaneously charged thereby, acondenser discharge circuit connected across said second condenser meansand comprising normally open circuit-closing means responsive to apredetermined charge on said second condenser means for closing saidcircuit, and a second condenser discharge circuit comprising othernormally open circuit-closing means and said first and second condensermeans connected in series across said first-named circuit-closing means,said other circuit-closing means being responsive to the sum of thecharges on said first and second condenser means to close said seconddischarge circuit while said first-named circuit-closing means isoperative.
 10. Electrical pulse-generating apparatus comprising a sourceof electrical energy, first and second condensers connected to becharged in parallel by said source, a first spark gap connected betweenthe positive polarity terminal of one of said condensers and thenegative polarity terminal of the other of said condensers, a secondspark gap connected between the other terminals of said condensers, andcondenser discharge circuit means including said second spark gapconnected across and adapted to be rendered conductive by the charge onsaid second condenser, whereby said condensers and said second spark gapbecome connected in series across said first spark gap while the secondspark gap is conductive.
 11. Electrical pulse-generating apparatuscomprising a source of electrical energy, first and second storagecondensers connected in parallel across said source to be simultaneouslycharged thereby, a first discharge circuit comprising said firstcondenser and a first spark gap adapted to be rendered conductive by apredetermined charge on said first condenser, and a second dischargecircuit comprising said first gap and said first and second condensersconnected in series across a second spark gap having a spark-overvoltage less than the sum of the charges on said condensers when saidfirst gap is rendered conductive.
 12. Electrical pulse-generatingapparatus comprising a source of electrical energy, first and secondstorage condensers connected in parallel across said source to besimultaneously charged thereby, first and second normally conductivespark gaps, a first discharge circuit comprising said condensers andsaid spark gaps connected in series, and a second discharge circuitcomprising said second condenser in series with said second spark gap,the latter being adapted to be rendered conductive when said secondcondenser attains a predetermined charge, and said first spark gap beingadapted to be rendered conductive in response to the sum of the chargeson said condensers when said second spark gap is rendered conductive.13. Apparatus as defined in claim 12 comprising a transformer havingprimary and secondary windings, said primary winding being seriesconnected in said first discharge circuit, a third spark gap connectedacross said secondary winding, and a third discharge circuit comprisingsaid second spark gap, said secondary winding and said third spark gapconnected in series across said first condenser.